epsilon0 = 8.854187817e-12;
syms epsilon epsilon_infity wp w gamma sigma_eff
epsilon1 = epsilon_infity - (wp^2)./(w*(w+1j*gamma));
sigma_eff =  (wp^2)./(w*(w+1j*gamma))*1j*w*epsilon0;
% epsilon = epsilon_infity...
%     -wp^2/(w^2+gamma^2)...
%     +1j*(wp^2*gamma)./(w*(w^2+gamma^2));

w = 3e6*2*pi;
wp = 1370e12*2*pi;
gamma = 4.08e13;
epsilon_infity = 10;
% eval(epsilon)
eval(epsilon1)
abs(eval(sigma_eff))

%% 电导率为实数

syms sigma epsilon2
sigma = 4.561e+007;
epsilon2 = epsilon_infity+1j*(sigma/w/epsilon0);
epsilon2

%% 
test = 1j*wp^2/gamma/(w+1j*gamma)